1. Field of the Invention
The present invention relates to a process for producing isotopes, and more specifically, the present invention relates to a process for producing isotopes via nuclear reactions with an accelerator beam on various targets.
2. Background of the Invention
The alpha-emitting radioisotopes 225Ac (Actinium) and 213Bi (Bismuth) are being used in clinical trials for cancer therapy. Presently 225Ac is made available only via processing of materials irradiated for years in reactors. For example, the actinium isotope is a product of decay of 229Th, which in turn is produced via decay of 233U, which in turn is produced via neutron irradiation of 232Th. The isotope 213Bi is a product of the decay of 225Ac.
Potential feedstock for the actinium isotope includes approximately 27,000 kilograms (kg) of irradiated light water breeder reactor (LWBR) fuel, which requires processing. If the entire mass of this large volume of LWBR fuel is processed, 5,000 millicuries (mCi), or 5 Ci of 225Ac could be produced per month.
225Ac can also be produced via cyclotrons or photonuclear methods using 226Ra as feedstock. 226Ra is also only available in limited quantities as a byproduct of irradiated reactor fuel.
Currently utilized methods for producing 225Ac and its associated daughter isotope 213Bi yield very small quantities, about 500 mCi per year. This limited quantity cannot support the present demand for clinical trials. Indeed, a survey at the 10th International Symposium of the International Isotope Society in 2009 estimated a more than ten-fold increase in demand from 2008 to 2012 for 225Ac for clinical trials alone. If the aforementioned clinical trials are successful, there will be an even much larger demand for these isotopes in the future.
Separately, the National Academy of Sciences has emphasized the need for larger quantities of such isotopes, inasmuch as these cocktails may rapidly become the treatment modality of choice for cancer patients.
The current state-of-art is to extract Th-229 from spent fuel. The presently available supply of 225Ac from this process at Oak Ridge National Laboratory is about 500 mCi per year. Taking into account all available irradiated material in the U.S., the rate could be increased to about 5 Ci per month by separations from tons of the highly radioactive source material.
In light of the foregoing, currently utilized methods are not a viable long-term solution for the production of the expected large quantities required of therapeutic isotopes.
A need exists in the art for method for producing abundant quantities of short-lived therapeutic isotopes, such as 225Ac, 213Bi, and other clinically relevant isotopes. The method should be capable of meeting the anticipated demand for these relevant isotopes and potentially cost less than state-of-the-art production methods. Furthermore, the method should utilize currently available technology.